Cathode ray device



Dec. 17, 1940'. F. KLAUER 2,225,455

CATHDE RAY DEVICE Filed Feb. 23, 1939 IAA f AA lllllll;j

INVENTOR. FRITZ KLAUER wwf@ ATTORNEY.

Patented Dec. 17, 1940 PATENT oFFlcl-z cA'rHoDE RAY DEVICE Fritz Klauer, Berlin-Charlottenburg, Germany, assig-nor to Siemens Apparate und Maschinen Gesellschaft mit'beschrnkter Haftung, Berlin, Germany, a corporation of Germany Application February 23,1939, Serial No. 257,905

' In Germany July 7, 1937 4 claims. (c1. 25o-15s) Myinvention relates to-improvements in cathode ray tubes of the oscillograph type andp-articularly in tubesv wherein a curvilinear orfcircuylar time base is utilzedfor indicating electrical phenomena. v l

It has been proposed in tubes of the prior art to utilize a cathode ray tube having a fluorescent screen. for measurements wherein the time base is evidenced byy a f closed curved trace onk the fluorescent screen. The time base may be formed on such a screen `byelectrostatic or electromagnetic means but it ,has been diiiicult to displace the electron beam of such tubes in a radial Vdirection in response to a signal to be measured inasmuch as the .tubes of the priorart have obstructing electrode supporting structure either in the path of the cathode ray beam or between the uorescent screen and the observer.

It is an objectv of my invention to provide a cathode ray tube suitable for observing transient phenomena by the displacement of a curvilinear or circular time base without the interposition of obstructing structure, and a, further obj ectto provide Vsuch a .tube wherein the sensitivity toelectrical phenomena to be measured is improved.

` In accordance with my invention I provide a cathode ray tube having a fluorescent screen with means to generate an electron beam and deflect the beam along a. curvilinear or circular path and Vfurther dellect the beam radially .to the said path rwith electrostatic structure entirely removed -from the path of the beam without the interposition of any obstructing medium Without the tube. These and other objects, features and advantages of `my invention will become apparent and will at once suggest themselves to those 4skilled in the art to which the invention is directed from the following ydescription taken in connection with the accompanying drawing in which; f Figure 1 is a longitudinal sectional view of cathode r-ay tube incorporating my invention; and,

kFigure 2 is a cross-section of certain of the electrodek structure shown in Figure 1 showing the electrostatic field generated in that structure. fIn the illustrative embodiment of my invention -as shown in Figure 1, the cathode ray tube comprises an evacuated envelope or bulb I having an rvelongated neck section enclosing an electron gun tional type and comprises a cathode'3 from which an electron stream may be drawn, a control electrode 4 connected to l the usual biasing battery and a rst anode 5 maintained vpositive With respect to the .cathode 3. The electron 5 stream leaving the first anode 5 is accelerated and concentrated into an electron scanning beam by a second anode 6 which is preferably a conductive coating on the inner surface of the bulb` l over` a portion of .the n-eck and frusto-conical sections. `l The iirst anode and the second anode 6 are maintained at the desired positive potentials by a-potential source such as the battery l. Conventional deflection means such as the electromagnetic coils 8 and 9 may be used to sweep `the `15 beam so as to* produce a curvilinear or circular luminous trace on the fluorescent screen! by applying alternating current to the coils 8 Which are leading or lagging the current applied .to the coils 9. It is obvious that conventional electrostatic plates may be substituted for the deection coils if desired whereupon thedeection plates-Would be supplied by alternating voltages having the desired phase relationship.

n Inv accordance with my invention I provide bef tween the' curvilinear or circular trace beam deiiecting means such as the .coil-s Band Sand a target adapted to'- become luminescent when Ibombarded with electrons such as the fluorescent screen 2, means for producing a non-homogeneous axially symmetric electrostatic 'eld `for deflecting the beam in'a radial direction with lrespect to the curvilinear or circular deiiection. A homogeneous electrostatic longitudinal eld does not exercise upon an electron moving in the direction" of this field anyv radially directed force'but` this elTect Will be produced by ya non-homogeneous axially symmetric eldfor the reason thatthere is set up a radial component of deflection in additionr to a local change in the longitudinal com, ponent of the field. Such an electrostatic field produces upon a beam of moving electrons an influence similar to that produced by an optical lens upon the path of luminous rays. y

More particularly I provide means for imp-art- 45 ving a radial component of velocity to a moving diaphragm electrodes Ill and II spaced longitudinally along the path of the beam with an intermediate apertured disc or diaphragm electrode I2 electrically insulated from the diaphragme I0 and I I which are electrically connected together. The electrically connected electrodes I0 and II are preferably supported in the neck of the tube within the second anode 6, and may have a potential applied thereto through the lead I3, the intermediate electrode I2 likewise being provided with a lead ICI. The diaphragms I D and II and the diaphragm I2 may be connected indirectly to the second anode 6 through a bridge network of equivalent resistors I5 and IS so that their mean potential may be maintained equivalent to that of the second anode. The impedance ofthe network is relatively high, the resistors 'having a resistance of around I megohm so that potentials, which it is desired to measure, unbalancethe network and produce an electrostatic deflection field between the electrode I3 and the electrodes II and l2.

vDuring operation of my new and 'improved cathode ray tube the deflection means, such as the coils 8 Yand 9, sweep the cathode ray beam so as to form a curvilinear or circular trace on the screen 2, the beam sweeping out and generating an imaginary cone having its apex at the center of deiiection of the coils 8 and 9 and its base on the fluorescent screen 2, the boundaries of which are indicated by the lines CA and CB in Figure 1. If it is assumed that radial deflection components exist in or adjacent the apertures of the diaphragms Il), II and I2, additional deflection of the electron beam occurs in the region of these electrodes thereby increasing or `decreasing the radial component of the beam produced by deflection coils 8 and 9. The imaginary cone swept out by the beam will, therefore, be modified. This modiiication of the path of the beam is shown in Figure 1 wherein the lines CA and CB change their direction slightly in the region of the electrodes Il), Il and I2 which presupposes that the electrode I2, with the divergence of the lines CA and CB as shown, is at a negative potential with respect to the electrodes Ill and II. The action of my new and improved electrode structure may be further explained with reference to Figure 2 which lshows the crosssection of the electrodes I0, II and I2 made by a cutting plane lying along the tube axis XY and in which the lines I1 show equipotential regions developed by the application of a potential difference between the electrodes. It will be observed that as the distance from the tube axis XY is increased the angle of inclination of the equipotential lines likewise increases. Since electrons moving through an electrostatic field of this nature are deviated from their initial path by an amount proportional to the angle of inclination of the equipotential lines, Ythe radial component imparted to the electron beam by such an electrostatic field will be proportional to its distance from the axis such as the axis XY. It is, therefore, preferable to make the apertures of the diaphragm electrodes Iii, II and I2 so small or the `diameter of the imaginary cone swept out by the beam in the region of these electrodes so large that the circularly deflected cathode ray beam will pass through the apertures relatively close to the solid portions of the electrodes.

In addition to theradial deection components produced by the electrostatic eld in the apertures of the diaphragm electrodes I0, II and I2 there is also a longitudinal component applied to the electron beam which in effect is a combination of accelerating and decelerating components. Therefore since lower velocity electrons are more radially deflected than are high velocity electrons, the longitudinal component of the electrostatic field existing in the apertures will determine the extent of the radial deflection imparted to the beam by the eld existing between the electrodes. It is, therefore, desirable to provide the electrodes I0, II and I2 spaced closely together in the direction of the tube axis. A spacing of 1 mm. between these electrodes has been found suitable although for various deflection sensitivities or various applied potentials this spacing may be either less or greater than the above mentioned value.

It will be obvious from the above description taken `in connection with the accompanying drawing that my tube is particularly adapted to the Ameasurement of electrical phenomena with the utilization of curvilinear or circular time base and that by the use of my structure I am able to produce a continuous uninterrupted trace on the uorescent screen and further that the fluorescent screen is unobstructed with respect to the observer in that no structure is interposed in the path of the light rays emanating from the uorescent screen. The electrical phenomena in effect will divert the beam from the normal curved path along a substantially straight line normal to the curve and extending in a radial direction which may be observed without any intervening obstructions. Therefore, while I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as serl forth in the appended claims.

I claim:

1. A cathode ray oscillograph tube comprising an envelope, a target adjacent one end of said envelope adapted to become luminescent when bombarded by high velocity electrons, an electron gun adjacent the opposite end of said envelope and exposed to said target to generate and direct -an electron beam along the axis of said envelope, means between the gun and target for sweeping the beam from said gun along a closed curved path on said target, and means comprising three closely spaced apertured disc electrodes surrounding a portion of and removed from the normal undeflected path of the beam for deflecting the beam from the closed curved path.

2. A cathode ray oscillograph tube having an envelope, an electron emitting cathode to produce a ow of electrons, an anode to produce a focused beam of electrons, a screen adapted to become luminescent when bombarded by electrons from said gun, means to deflect the electron beam from said gun over said screen along a closed curved path, a pair of apertured closely spaced disc electrodes enclosed within said anode in a substantially field-free space generated by said anode and between said deection means and said screen and an apertured disc electrode between said pair of disc electrodes to generate therewith a radial beam deflection held, the apertures of each of said disc electrodes being in axial alignment with each other and with said gun. 3. A cathode ray oscillograph device for measuring electrical phenomena comprising an evacuated envelope, an elongated electron gun to generate a beam of electrons, an electron receiving target exposed to said electron gun' and intersecting the longitudinal axis of said gun, beam deflecting means to deliect the beam generated by said gun from the longitudinal axis of said gun and along a closed curved path, a series of three apertured discs perpendicular to the longitudinal axis removed from and surrounding said axis, and means to apply the electrical phenomena to be measured between the central disc and the remaining discs.

4; A cathode ray oscillograph device for measuring electrical phenomena comprising an electron source to generate a stream of electrons,L a pair of associated anodes to accelerate and focus the stream of electrons from said source into-an electron beam, beam deflecting means to deflect the beam from its normal path, three apertured beam deecting diaphragms surrounding the normal undeected path of said beam Within one of said anodes and Wholly removed from the j normal undeflected path of said'bear'n, means to apply a potential difference between the innermost diaphragm and the other two diaphragms for additionallydelecting the beam from itsV initially deected path, and an electron receiving target in the path of the additionally deected beam.

FRITZ KLAUER. 

